FIG 2.
An EMS screen identified a mutant in argF that is required for both Pseudomonas growth and rhizosphere acidification. (A) A mutant, 10E10, was identified from an EMS screen for P. simiae mutants that cannot supress flg22-triggered induction of CYP71A12pro:GUS expression or (B) acidify the rhizosphere. An ΔargF mutant phenocopied the inability of the 10E10 mutant to suppress immunity suppression and acidification, and expression of argFpro-argF on a plasmid restored the immunity suppression and acidification of the 10E10 mutant. Addition of exogenous arginine lowered the pH of the ΔargF and 10E10 mutant, but resulted in alkalization of a ΔpqqF or a ΔpqqFΔargF double mutant growing in seedling exudates. All the experiments were independently repeated at least 3 times. Statistics were calculated by using one-way ANOVA and Tukey’s HSD. Error bars represent mean ± SD, and letters indicate differences at P < 0.05. (C) The mutation in the 10E10 mutant is within the catalytic site of ΔargF, and results in a predicted loss of function mutation. (D) The 10E10, the ΔargF, and the ΔargFΔpqqF mutants had a growth defect in the seedling exudates. (E) Growth of ΔargF and the ΔargFΔpqqF mutants were rescued by the addition of exogenous arginine.